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Texting or some hands-free talking behind the wheel is as dangerous as being over the limit

March 15, 2013

High-cognitive-demand conversations or testing behind the wheel is as dangerous as being twice over the limit (credit: SINC)

Using a handsfree kit or sending text messages is the same as being above the legal alcohol limit, an experiment by Scientists from Australian universities in collaboration with the University of Barcelona has demonstrated.

The Australian universities of Wollongong, Victoria, Swinburne of Technology, the Institute for Breathing and Sleep, and the University of Barcelona measured the reaction capacity behind the wheel of 12 healthy volunteers who participated in a driving simulation test lasting two days, each a week apart.

They took the highway driving test under two conditions: after consuming alcohol and while using a mobile phone hands-free (headphones and a microphone were used to simulate the handsfree effect) or texting.

“We conducted the study in Australia and the participants, who were volunteer students holding a driving licence, had to keep their position in the centre of the left lane on the screen at a speed of between 60 and 80 kilometres per hour, breaking every time a lorry appeared,” said Sumie Leung Shuk Man, co-author of the study published in the Traffic Injury Prevention journal and researcher at the University of Barcelona.

Hands-free with high cognitive demand, text users performed equivalent to alcohol over legal limits

By comparing the blood alcohol concentration (BAC) with the effects of mobile phone usage, they saw that when the conversation using the hands-free was simple, the effects were comparable to a BAC level of 0.04 g/l, which is below the legal limit of 0.5 g/l in countries like Spain and Australia.

However, when the telephone conversation required high cognitive demand, their equivalent alcohol level analog shot up to 0.7 g/l — above legal limits in both countries (0.5 gram/litre) … yet below in other countries, like the USA or the UK, where up to 0.8 g/l is allowed.

When texting, the level shot up to 1 g/l, which is illegal in any of all of these countries.

The two different handsfree conversation levels studied are the equivalent to: a natural conversation in which the subject and the scientist speak about an interesting subject but as a way of passing the time; and a dialogue with more specific, cognitively demanding questions, such as “can you describe the car journey from your work to your house?” or “how many of your friends have names that begin with a vowel?”.

“Our results suggest that the use of handsfree devices could also put drivers at risk. Although they should be allowed, they require more research to determine how they should be regulated and, of course, the thorough knowledge that national authorities should have regarding their pros and cons,” concludes Man.

Comments (7)

Ok if this is dangerous, what about pilots? They are wired all the time and have been for decades, yet I have never heard of an accident caused by a pilot on the radio. This article is a bit too sensational and speculative for a science-oriented site like this.

Right, if a pilot’s attention lapses for a few seconds, it’s unlikely to be fatal… not so on the road. This isn’t a novel finding, but it’s another illustration of how inherently limited human drivers are… our poor brains can only attend to one stimulus at a time. That’s one of the reasons robot cars will be so much safer (and then there’s their superior reaction times, of course).

“This article is a bit too sensational and speculative for a science-oriented site like this.”

The study was funded by a collaboration between universities, and is published for peer-review. Meanwhile you offer criticisms based on anecdotal stories: “I’ve never heard of…….” It is clearly YOU who do not understand science.